Role Of Natural Killer Research Articles

Role of natural killer (NK) cells and interferon in self-defense meahanisms.

Role of natural killer (NK) cells and interferon in self-defense meahanisms.

Symposium on mechanisms of host defense from fundamental and clinical medicine. 2. Role of natural killer (NK) cells and interferon in self-defense mechanisms

Symposium on mechanisms of host defense from fundamental and clinical medicine. 2. Role of natural killer (NK) cells and interferon in self-defense mechanisms

The mechanism of augmentation of natural killer cell activity by syngeneic tumor cells: role of macrophage-derived factor in NK boosting.

The role of natural killer (NK) cells in controlling tumor growth was investigated using an NK-susceptible (c127v-IC2) and an NK-insusceptible (c127av) subline of the lymphoma L5178Y. Syngeneic DBA/2 mice inoculated intraperitoneally with c127v-IC2 tumor cells survived significantly longer than did c127av-bearing mice. Similarly, c127v-IC2, but not c127av tumor cells, were found to augment NK activity of spleen and peritoneal exudate cells in both DBA/2 and BALB/c nu/nu mice when inoculated into the peritoneal cavity. C127v-IC2 tumor cells incubated with either DBA/2 or BALB/c nu/nu spleen cells in vitro boosted NK activity and induced the production of gamma-type interferon (IFN), whereas incubation with c127av tumor cells induced neither NK activity nor IFN. Two kinds of cells cooperated in the production of IFN in response to c127v-IC2 tumor cells, namely, cells which were nonadherent, bore asialo-GM1, NK-1.2 and a low level of Thy-1.2 antigen and thus closely resembled NK cells, and those which were adherent and phagocytic and lacked both asialo-GM1 and NK-1.2 markers, presumably macrophages. Further analysis strongly suggested that c127-v-IC2 tumor cells stimulate macrophages to produce factor(s) which can induce the production of IFN by NK cells. The induced IFN was shown to be of the gamma type by its lability at pH 2.0 and insusceptibility to anti-IFN alpha, beta serum. This suggests a novel pathway for NK cell activation, and strongly supports the importance of macrophages and NK cells in natural resistance against certain tumors.

The acquired immune deficiency syndrome (AIDS) in hemophiliacs: a hypothesis.

Healthy hemophiliacs receiving antihemophilic (AHF) concentrates have decreased T-helper/suppressor (H/S) ratios, similar to the changes observed in healthy homosexuals considered at risk for the acquired immune deficiency syndrome (AIDS). We present a hypothesis which focuses on the role of natural killer (NK) cells and elevated serum levels of alpha interferon (IFN alpha) in hemophiliacs with AIDS. This hypothesis suggests that alloantigens in AHF concentrates provide an important inducing event which compromises the immune system of the hemophilia patient and enhances his susceptibility to infection by a transmissible agent. It provides an explanation for the predominance of NK cells with T-cell markers, impaired NK cell function, elevated serum IFN alpha levels, and the deficit in T-helper/inducer cells in hemophilic patients with AIDS. Furthermore, it could account for the T-cell subset imbalance in relation to total AHF units transfused, and to the development of an inverted H/S ratio which is a constant feature of AIDS.

Role of Natural Killer Cells in Tumor Growth and Metastasis: C57BL/6 Normal and Beige Mice<xref ref-type="fn" rid="FN2">2</xref><xref ref-type="fn" rid="FN3">3</xref>

The role of natural killer (NK) cells in tumor growth and metastasis was studied in syngeneic normal and beige inbred C57BL/6 mice. Mice with the beige point mutation have been shown to be deficient in nonstimulated NK activity. Tumor-passaged B16 malignant melanoma cells were refractory to NK activity as determined by in vitro assay, but after in vitro culture they became sensitive to NK activity. The NK-insensitive B16 tumor grew and metastasized similarly in normal and beige mice. However, the NK-sensitive B16 tumors grew more slowly and produced fewer metastases in normal mice than in NK-deficient beige mice. Activation of NK cells by lymphocytic choriomeningitis virus infection decreased the rate of growth and number of metastases of both NK-sensitive and NK-insensitive tumors in both normal and beige mice. These results suggest the importance of NK cells as a determinant of tumor growth and metastasis.

The role of natural killer (NK) cells in resistance to herpes simplex virus I (HSV‐I) infection

Summary Pretreatment of mice with cyclophosphamide (CY) increases susceptibility of adult mice to herpes simplex type I (HSV‐I) infection. In searching for a CY sensitive mechanism, our attention has been focused on natural killer (NK) cells. Activity of these cells was increased in spleens of adult mice after inoculation with HSV‐I and depressed after CY administration. The timing of recovery of NK cell activity after the administration of CY, was consistent with a role for these cells in collaboration with immune T lymphocytes when transferred to pre‐treated, virus infected animals. It is postulated that sensitized T lymphocytes reacting with virus antigens release products that activate macrophages which in turn produce interferon. Interferon increases NK cell activity and NK cells inhibit viral replication. A correlation between resistance to HSV‐I infection and NK cell activity of CBA or C57BL/10 mice was found. It is suggested that NK cells play a role in defence, not only against tumour cells, but also against a wide range of infective agents.